The goal of this work is to better understand how auxiliary alpha2delta subunits modulate neuronal voltage-gated calcium channels (VGCCs) which affect neuronal migration (Komuro, et. al,1998), synaptogenesis (Bahls, et. al., 1998), and neurotransmission (Dunlap, 1995). Neuronal VGCCs consist of an alpha1 pore subunit and auxiliary subunits, alpha2delta, beta, and possibly gamma, which differentially regulate channel properties (Catterall, 2000). Studies in heterologous expression systems suggest that alpha2delta subunits associate with alpha1 and modulate channel function by altering the membrane trafficking and biophysical properties of VGCCs (Klugbauer, et. al, 2003). However, the in vivo function of alpha2delta in regulating pore-forming alpha1 subunits is less clear. Several straightjacket (stj) mutants with genetic lesions in the Drosophila alpha2delta subunit have been isolated. Initial electrophysiological and EM studies of stj mutants hint at defects in vesicle fusion. I propose to study the in vivo function of Drosophila alpha2delta, focusing on its role in regulating neuronal VGCCs and neurotransmission. Initially, I will generate null alleles of alpha2delta to aid in the genetic characterization of isolated mutations. I will then investigate VGCC trafficking in stj mutants using a fluorescent-tagged alpha1 pore subunit. In addition, I will determine whether alpha2delta modulates channel function using calcium imaging. Finally, I will explore whether interactions between alpha2delta and beta are necessary for proper VGCC function.